Interactive effects of growth factors and three-dimensional scaffolds on multipotent mesenchymal stromal cells

The creation of tissue-engineered constructs with autologous cells is a central goal in regenerative medicine. With respect to ligament replacement, we have evaluated the influences of matrix and growth factors on hMSCs (human mesenchymal stromal cells). hMSCs were seeded in two different 3D (three-dimensional) systems consisting of either a collagen type I gel or a synthetic PLA [poly-(L-lactic acid)] scaffold. After cultivation for 14 days with rhTGF beta 1 (recombinant human transforming growth factor beta 1), rhPDGF-BB (recombinant human platelet-derived growth factor homodimer of B-chain) or rhBMP13 (recombinant human bone morphogenetic protein 13), we assessed the proliferation potential, mRNA expression and protein expression of various matrix-interacting and matrix-degrading molecules by quantitative real-time RT (reverse transcriptase)-PCR, immunohistochemistry and gelatin zymography in comparison with unstimulated cells. Cellular reactions to the type of scaffold or soluble factors could be found in the expression of tenascin-C as well as integrin subunits alpha 1, alpha 3 and beta 1. Collagen type X expression was induced by 3D culture and stimulated by rhTGF beta 1 on PLA. The expression of MMP-1 (matrix metalloproteinase 1) tended to increase, and MMP-13 was induced in the collagen culture system. The activation of MMP-2 was stimulated by the cultivation of MSCs within the collagenous matrix. These results demonstrated that various interactive effects of growth factors and scaffolds influence the cell-biological behaviour of MSCs. It is important to take these complex interactions, which partly differ from differentiated cells, into account in further tissue-engineering approaches.